Intro to anaemia and microcytic anaemia

Question 1

What is the definition of anaemia?

Answer 1

a reduced total red cell mass

Question 2

What is used to measure whether a person is anaemic?

Answer 2

Red cell mass is not easy to measure.
Haemoglobin is used as a surrogate.
Haematocrit can also be used.

Question 3

What is the normal range of haemoglobin in an adult male and female

Answer 3

Male >130g/L

Female >120g/L

Question 4

What is haematocrit?

Answer 4

A ratio or percentage of the whole blood that is red cells if the sample was left to settle (or centrifuged)

Question 5

When may haemogblobin not be an acurrate marker?

Answer 5

In an acute bleed

If there is an acute increase in plasma volume (ie IV fluids have been given)

Question 6

what is a reticulocyte

Answer 6

Red cells that have just left the bone marrow but are not yet mature reticulocytes

Question 7

what is the difference between reticulocytes and RBCs

Answer 7

larger
still have remnants of protein making machinery such as RNA
therefore stain purple/deeper red
blood film is polychromatic

Question 8

What happens in response to anaemia

Answer 8

Increased red cell production

peripheral blood reticulocytosis

Question 9

Where in the cell does haemoglobin synthesis occur

Answer 9

in the cytoplasm

Question 10

why does a small mean cell volume (microcytic) indicate a problem with haemoglobinisation?

Answer 10

hb synthesis occurs in cytoplasm so defects result in small cells

Question 11

What are the components of Hb

Answer 11

Globins - two alpha and two beta chains (gamma in fetus)

Haem= porphyrin ring and iron

Question 12

What results due to a shortage of the components of haem

Answer 12

Small cells (microcytic) with low Hb content. 
Hypochromic cells (lacking in colour).

Question 13

So what do hypochromic, microcytic anaemias indicate?

Answer 13

defective haemoglobin synthesis - cytoplasmic defect

Question 14

What are the causes of hypochromic micricytic anaemias

Answer 14

Haem deficiency=

• iron deficiency (either low body iron or due to chronic disease but this can be normocytic) - COMMON
• porphyrin synthesis (lead poisoning or pyridoxine responsive anaemias)-RARE
• congenital sideroblastic anaemias - RARE

Globin deficiency=
-thalassaemia

Question 15

When is iron toxic in the body

Answer 15

Free iron is toxic

Must be bound to transport proteins

Question 16

What is type of iron is contained in a haem group

Answer 16

Fe2+

Question 17

How much oxygen can each haem group bind`

Answer 17

One O2 molecule

1.34ml of O2 in a saturated haem molecule

Question 18

How is iron stored in the body

Answer 18

In tissues (liver) as ferritin
As haemoglobin in RBCs
As ferritin in macrophages`

Question 19

What is transferrin

Answer 19

Transports iron from donor tissues (macrophages, hepatocytes) to tissues expressing transferrin receptors eg bone marrow

Question 20

How many binding sites does transferrin have for iron atoms

Answer 20

two

Question 21

What does the percentage of saturation of transferrin with iron measure

Answer 21

Iron supply in the body

ie it is reduced in iron deficiency and anaemia of chronic disease but increases in genetic haemachromatosis

Question 22

What is ferritin

Answer 22

A large intracellular spherical protein

It is how iron is stored in tissues

Question 23

What does serum ferritin indicate

Answer 23

It is an indirect measure of storage iron

Low ferritin = iron deficiency

Question 24

How is iron deficiency confirmed>

Answer 24

By a combination of microcytic hypochromatic anaemia and reduced iron storage (low serum ferritin)

Question 25

What are possible causes of iron deficiency

Answer 25

Dietary insufficiency - either RELATIVE (young women and children) or ABSOLUTE (poor diet)- this is unlikely in men
Blood loss -usually GI (ulcer or tumour), menorrhagia, haematuria
Malabsoption- Coeliac, achlorhydria

Question 26

What are the consequences of negative iron balance

Answer 26

1. Exhaust iron stores
2. Iron Deficient erythropoiesis - decreasing MCV
3. Anaemia
4. Epithelial changes eg skin, koilonychia

Question 27

What is meant by occult blood loss

Answer 27

A small, ongoing loss of blood without noticeable signs or symptoms of bleeding
Can cause anaemia